Field of the Invention
The present invention relates to a lens barrel with collapsible lens groups, and an image pickup apparatus.
Description of the Related Art
Image pickup apparatuses such as cameras and video cameras have lately increased in magnification and decreased in size. Accordingly, some lens barrels provided in image pickup apparatuses are configured to collapse lens groups. Namely, when shooting is not performed, at least some lens groups in a lens barrel collapse while retracting from an area on a shooting optical axis, and when shooting is to be performed, the lens groups are extended from a camera casing so that the distances between the lens groups can be suitable for shooting.
A lens barrel according to Japanese Laid-Open Patent Publication (Kokai) No. 2012-042649 retracts a focus lens group when an image pickup apparatus which is a camera is brought from a shooting state to a collapsed state, so that the length of collapsing when housing into the lens barrel can be reduced to make the image pickup apparatus smaller. Also, a lens barrel according to Japanese Laid-Open Patent Publication (Kokai) No. 2010-262107 mechanically inhibits movement of a lens to be inserted until retractable lenses have been completely retracted. After the retractable lenses have been completely retracted, the lens is inserted.
Conventional lens barrels are generally configured to retract a retractable lens group while moving the whole lens groups in a housing direction. In this case, allowance needs to be made for the layout and operation of the lens groups in the direction of the optical axis, and there is scope of improvement for efficient shifting to a collapsed state and reduction of the thickness of a lens barrel. According to Japanese Laid-Open Patent Publication (Kokai) No. 2012-042649 as well, a lens group that is located lateral to a retracted focus lens group when a lens barrel is collapsed simply moves in one direction in a direction of an optical axis during shifting to a collapsed state. It is thus necessary to allow leeway for distances between lens groups so as to prevent interference between them so that the lens groups can be put at retracted positions after the focus lens group is completely retracted.
Moreover, according to Japanese Laid-Open Patent Publication (Kokai) No. 2012-042649, the focus lens group is retracted to an outer side of the outermost diameter of the lens barrel, and hence not only the lens barrel is large in size, but also the reliability may be lowered in terms of strength and environmental resistance due to a hole for retraction formed in a side face of the lens barrel. Further, a driving source for zooming and a driving source for retracting the focus lens group are provided independently, which makes the arrangement of the lens barrel complicated.
On the other hand, according to Japanese Laid-Open Patent Publication (Kokai) No. 2010-262107, a mechanical component for inhibiting movement of a lens to be inserted by mechanically stopping it in an engaged state is required, and this not only makes the arrangement of the lens barrel complicated but also may cause a load put by the stopping action to affect the lens barrel. For this reason, an arrangement that efficiently brings a retractable lens group and an inserted lens group into a collapsed state without increasing the load on a lens barrel or increasing its overall size is demanded.